Hey everyone, with my paid Xsplit license about to expire, I decided it was high time to play around with OBS, here are some findings between the two:
1: General friendliness and UI
I'm pretty happy with both programs, although Xsplit gets a very small lead here, OBS is also fairly well polished. Both offer you an easy fast way to swap between scenes and control microphone vs computer source volumes to balance them. I found it a little harder to add content to OBS than Xsplit, but it wasn't overly complicated.

Xsplit, however, does pull a huge win when it comes to adding multiple sources to a single stream. The ability to "drag" around and resize and always see a live preview gives Xsplit a very nice win over OBS on this area. It won't be a feature most people will need, but if you plan to have many different sources making up your stream (i.e. adding custom logos, webcam, maybe a video, graphics, etc), this may or may not bother you. OBS gives you options to change how each source shows up/where it is, but these controls are all through menus and settings... will take you a lot more time to get it perfect.

Getting into the settings and configuring your stream is pretty easy on both and I find that OBS is about 2% better here due to a couple extra options. Nothing big. Also, it should be noted that OBS does support custom plugins, although at the time of posting it seems most or all of them are for automatic scene switching.

2. Stream quality:
Didn't notice any significant difference in quality between Xsplit and OBS, the quality diff I noticed was probably because I accidentally had OBS at 1400kbps instead of 1500kpbs. Both seem to offer very similar quality for the same bitrate, but OBS offers more high quality settings than the free version of Xsplit (which is important to note since OBS is free and the premium settings on Xsplit cost you a subscription fee).

3. Performance testing:
So, now that we know a few basics about using the programs and stream quality, let's see which one gives us better performance (if at all). For the test, I ran StarCraft 2 benchmark program that puts a large battle on the screen to stress the CPU and provide some scenes without a lot of motion, and some with many units milling around. For each program, I ran the benchmark once in SC 2 without benching, then I ran 3 tests and benchmarked with FRAPS each of the 3 runs while streaming. I then closed the program before switching to the other streaming program and repeated the process. After more use, I've had a couple experiences where OBS just doesn't send your stream to twitch properly and requires you to stop and start stream again to fix. Minor, but a problem.

4. Conclusion?
While I would give (paid) Xsplit the win based on a few factors, I will suggest OBS for most users. Xsplit gives slightly better performance, but it is so small it is hard to even say it performs better. Xsplit stream quality is only as good as OBS if you pay for it... and that is the main sticking point. Sure, Xsplit has better UI and makes it WAY easier to manage scenes and sources, but the fact that anyone wanting to go for a higher stream quality has to pay is just a deal breaker. Paid Xsplit pulls slightly ahead of OBS if you didn't care about price, but that difference is so small it's extremely hard to justify paying for a Xsplit subscription. Once OBS gets Intel quick sync working well, it will be a far superior choice, for most users, if Xsplit doesn't have an answer.
Xsplit:- Limited audio and stream quality without paid version
- Cannot capture game source (SUPER useful) without paid version
- Much easier to set up scenes and manage on the fly
- Very small performance lead over OBS

OBS:
- Free... did I mention you can get access to all features without needing a paid version?
- Very similar performance and quality of Xsplit
- Fairly easy to set up, has a couple options Xsplit doesn't (most people won't notice)
- Harder to set up and manage scenes, but can end with same results as Xsplit
- Plugin support (mostly auto scene switchers)